Mockito test case for class which calls another class in its constructor, in which 3 varibles are assigned inside them for legacy applicaiton in Java

I have a class below which calls another class in its constructor, in which 3 varibles are assigned, when I try to mock it I get

    java.lang.RuntimeException: Invoking the beforeTestMethod method on PowerMock test listener org.powermock.api.extension.listener.AnnotationEnabler@416dd4d8 failed.
    Caused by: org.mockito.exceptions.base.MockitoException: 
    Cannot instantiate @InjectMocks field named 'guidelinesProcessor' of type 'class com.psp.pca.businesslogic.GuidelinesProcessor'.
    You haven't provided the instance at field declaration so I tried to construct the instance.
    However the constructor or the initialization block threw an exception : null
Caused by: java.lang.NullPointerException
	at com.psp.pca.containers.GuidelineResultPageBean.<init>(GuidelineResultPageBean.java:8)
	at com.psp.pca.businesslogic.GuidelinesProcessor.<init>(GuidelinesProcessor.java:4)

GuidelinesProcessor.java

public class GuidelinesProcessor extends LogicProcessor {

private GuidelineResultPageBean pb;

public GuidelinesProcessor() {
pb = new GuidelineResultPageBean();
} 
public void process(Context ctx, Locale loc, PropertyBundle rb)	throws Exception {   
.....
}
}

GuidelineResultPageBean.java

public class GuidelineResultPageBean extends PageBean {
	private PackageDetails measurements;
	private Recommendation recom;
	private String guideline1 = null;
	private String guideline2 = null;
	private String guideline3 = null;

	public GuidelineResultPageBean() {		
		guideline1 = ResourceLoader.getProperties().getProperty(Constants.GUIDELINE1_STR);		
		guideline2 = ResourceLoader.getProperties().getProperty(Constants.GUIDELINE2_STR);
		guideline3 = ResourceLoader.getProperties().getProperty(Constants.GUIDELINE3_STR);
	}
}

Constants.java

public class Constants {
public static final String GUIDELINE1_STR = "guideline.1";
	public static final String GUIDELINE2_STR = "guideline.2";
	public static final String GUIDELINE3_STR = "guideline.3";
}

where

guideline.1 = "P1"
guideline.2 = "P2"
guideline.3 = "P3"

Below is my test class:

@RunWith(PowerMockRunner.class)
@PrepareForTest({ ResourceLoader.class, Context.class, Logger.class })
public class GuidelinesProcessorTest {

PropertyBundle mockrb;

@Mock
Context ctx;	
@Mock
GuidelineResultPageBean pgbean;    

@InjectMocks
GuidelinesProcessor guidelinesProcessor;  


@Before
public void setUp() {
MockitoAnnotations.initMocks(this);
PowerMockito.mockStatic(ResourceLoader.class);  
mockrb = new PropertyBundle();
mockrb.setProperty(Constants.KEY_LWH_UOFM_ENGLISH_CA, "in");
mockrb.setProperty(Constants.KEY_WT_UOFM_ENGLISH, "lbs");
mockrb.setProperty(Constants.KEY_LWH_UOFM_ENGLISH, "inches");		
when("guideline.1").thenReturn("P1");
when("guideline.2").thenReturn("P2");
when("guideline.3").thenReturn("P3");
}

@Test
public void testProcess() throws Exception {
loc = new Locale("en", "US");

GuidelinesProcessor guidelinesProcessorSpy = Mockito.spy(new GuidelinesProcessor());
Mockito.doReturn(pgbean).when(guidelinesProcessorSpy);

guidelinesProcessor.process(pgf, loc, mockrb);
}
}

Basically it is not able to invoke

PGAResourceLoader.getProperties().getProperty(Constants.GUIDELINE1_STR)

It will be of great help, if someone can help me with the correct way of mocking it.

You can do the following

@Mock
private Context ctx;   
 
@Mock
private GuidelineResultPageBean pgbean;    

private GuidelinesProcessor guidelinesProcessor;  


@Before
public void setUp() {
    guidelinesProcessor = PowerMockito.mock(GuidelinesProcessor.class, CALL_REAL_METHODS);
    Whitebox.setInternalState(guidelinesProcessor, "fieldName", pgbean);
    Whitebox.setInternalState(guidelinesProcessor, "fieldNameContext", ctx);
    // continue
}